1. Technical Field
The present invention relates to a charged particle beam apparatus.
2. Description of the Related Art
As an apparatus for processing and observing the surface of a sample such as a semiconductor device, a charged particle beam apparatus is known (see, for example, JP-A-2007-294391). The charged particle beam apparatus has a stage which holds a sample, a charged particle beam tube which irradiates a charged particle beam onto the surface of the sample held on the stage, a detector which detects secondary electrons emitted from the surface of the sample due to the irradiation with the charged particle beam, and an image forming unit which forms an image of the surface of the sample based on the detected secondary electrons.
This charged particle beam apparatus can be used, for example, to count repetitive patterns formed on the surface of a sample. In this case, the charged particle beam apparatus irradiates a charged particle beam along the repetitive patterns, thereby obtaining an image, and counts the patterns shown in the image. By counting the patterns, it is possible to specify, for example, a designated pattern from among the repetitive patterns. Under the circumstances, in order to display images of different positions of the surface of a sample, mainly, the stage is moved.
However, in a case of performing counting while moving the stage, vibration, drift, or the like of the stage may occur, whereby images may be deteriorated, which can become a factor of incorrect counting. Also, in recent semiconductor devices, there is a case where repetitive patterns are formed, for example, with a pitch of 20 nm or less. In this case, since the accuracy of fine movement (about 10 nm) of the stage is required, vibration, drift, or the like of the stage becomes a factor of incorrect counting. Like this, in a case of observing the surface of a sample while moving the stage, there is a case where observation accuracy decreases due to influence of vibration or the like of the stage.